The present invention described herein relates generally to a method and apparatus for installing a seal. More specifically, the present invention relates to a method and device for replacing a seal in the bearing of a wind turbine.
A pitch blade drive in a wind turbine acts on the blades of a wind turbine for changing their respective angles to achieve desired power or performance. For this reason, blades are pivotally guided around a longitudinal axis by bearings. Accordingly, the pitch blade drive requires the provision of a seal to prevent lubricant from leaking out and to prevent dust, water, and other contaminants from entering the pitch blade bearing. The wind turbine pitch blade bearing is usually provided with an outer seal and an inner seal.
Wind turbine bearings are generally designed for the life of the wind turbine. Seals that retain grease inside the bearing and protect it from different weather and contamination conditions, however, are not designed for such a lifetime. Therefore, such seals should be replaced with new ones periodically due to wear, dust, etc. Exact seal lifetime is not easily determined as it depends mainly on weather and contamination conditions, but as a reference, seals may be replaced about every three years.
Removal of an old seal from the wind turbine pitch bearing in situ or during pitch bearing manufacturing is currently very easy and quick as a seal is only needed to be pulled out from a bearing groove or seat. However, assembling a new seal into a wind turbine pitch bearing mechanism in situ (for example, when it is necessary for a seal to be replaced) or during pitch bearing manufacturing is currently a very difficult and slow operation. Such an in situ operation on a wind turbine usually involves an operator working at a height of over eighty meters from the ground, this being a hazardous and physically taxing working condition, and taking into account that operations may have to be performed external to the hub or within the confined spaces inside the hub.
One known method for facilitating the operator insertion of the seal into the bearing groove or seat of a wind turbine pitch bearing uses manually operated tools (e.g., hammers, pry bars, screwdrivers, etc.), and may also require the pitch motor(s) to be removed. However, they are time consuming and capital intensive because of high technical labor costs involved. Time required for the assembling of a new seal using manually operated tools involves undesirably long downtimes in which no electricity is produced by the wind turbine.